When something is dying off, it is slowly disappearing or coming to an end. There are numerous synonyms for the phrase "dying off," including dwindling, waning, fading, declining, or dwindling away. These words can be used interchangeably in a sentence, depending on the context and the desired tone. For example, if an endangered species is dying off, usage of the word dwindling would create a more somber or serious tone as compared to the word fading, which could infer a more gradual process. Similarly, if a fad or trend is dying off, the word waning could be more appropriate to describe the gradual decline. In summary, there is no shortage of synonyms to describe the process of dying off, and each word can be chosen based on the desired tone or context of a sentence.